Portable pneumohydraulic closing mechanism for circuit breakers



Sept. 23, 1958 E. R. PERRY x-:TAL 2,853,055

PORTABLE PNEUMOHYDRAULIC CLOSING MRCHANISM RoR CIRCUIT BREAKERS Filed Jan. 31, 1955 2 Sheets-Shet 1 PORTABLE PNEUMOHYDRAULIC CLOSING MECHANISM RoR CIRCUIT BREAKERS Filed Jan. 31, 1955 Sept. 23, 1958 E. R. PERRYV ETAL 2,

2 Sheets-Sheet 2 M14/WOW r. dA Wm l im @MM/@MMM LEMA JMX/MAO qxl nited States Patent Myice PORTABLE PNEUMonvuRAULIC CLQSIG MECHANISM FoR CIRCUIT BREAKERS l Elijah r-R. Perry, Stoughton-and Julius W..Timmerman,

"North' WeymouthrMass., assi'girs to Allis-Chalmers HManufacturing Company, Milwaukee, Wis.

Application Jannarysi, 1955, serial No. tsszs 4 claims. (cn A12141-38) vlaiiis'ms' l andl more? particularlyfto aV portable power closing 1 deviceiand'- parts thereoffor' closing ai circuit'breaker on `anenergized` system.

When -cireuit -breakers -are closed; on ran" energized Apower 'system they-must be closed rapidly -to reduce or eliminate excessively burning of the engaging contacts. IF or `this reason, power circuit breakers'are providedwith -fal`high speedcontactclosing mechanism which -usually -emp1oys either -a solenoidlor-compres'sed `air means `to supply ythe-energy needed to rapidlyclose the engaging contacts.

VIt occasionally -happeris` however," that thev4 souvrce 'of yelectrical energy supplyingthe solenoid or the compres- 1 son of: -the compressed air means is` 4 temporarily lost as,

ifor iexam'ple, Y'by tthe failure aigcont'rolz power trans- `former. Also,-ithee -a-re` other ldifficulties which, a1-

though insignificant in themselves, may prevent'theruse of the normal inethod of 'closing, :a ffewjexamples of whichaarez'burnout off'a closing' solenoid, control relay or .rectiertand da-mage to a-l controlJ sw'itcli` or to `control fwirin'g. fHowever, if av safetnethod 'of emergency Aclosing iisY available, a t consequent-untimely vandI possibly *costly interruption of service can be averted.

art arecapableof closing -bieakersother than tluie'very `smallest, only 'at subnormal speeds, thereby i.i'ncuf r1- ing ln order to provide meanse'adequateffor thecircuit- #switching operations yof abrea'ker `whose normalclosing means is incapacitated and-atthesametimeelirninate the `hazards `of`manu`ally closing such'a breaker, a fnew and improved pneumohydraulic emergency closing Jdevice has been provided which furnishes theinstantaneous Patented Sept. 23, 195% lopens to bypass hydrauliciiuid4 back to the pump reservoir when maximum safe operatingV pressure is reached "and a hydraulic operating fluid motor.

4 IThe iiuid motor is connected to the breaker operating `linkage by an easily 'detachable bracket. When the 'f emergency closing device is to be used to close a circuit breaker,the liiuid motor is attached to the'breaker by 'means of the bracket.

Then the hand pump is operated until"A full operating pressureis built up in the accumulator. HA'pressure gauge gives `a Visualindication ofthe pressure within the accumulator. Full operating pres- 'S'ureis built up in'less than one minute. A springfbiased valve prevents the'y releasing of oil from the 'accumulator tothefluid'motor, unless there lis 'adequatel'pressure to'insure a successful closingjoperation. v

After suiicient pressure'has` been"bu`i1t up, aci-Osing stroke may be initiated by moving the operating lever on the device to the closepositio'n. 4The operating fvalve automatically goes to full'open position as' soon as itis released. Thus, the full operating pressure in the 4accur'nulator is instantly transmitted vto the uid motor.

`The piston of 'the motor transmits thisenergy to the breaker operating linkages to close the" circuit breaker at its lnormal speed. y

"Itis,v therefore, one objectjof the lpresent invention 'j'to provide a new and improved pneumohydraulic'emergencyfpower closing device for clrcnit breakers.

Anotherobject of this invention is toi-provideainew "and improved ymanualpovver closingl device, for circuit vvctntactsiat-'a'speed' equal to orfgreater than the 'speed of 'lthe circuit Abreaker contact closing'mechanism.

breakers which can closea circuif'b'rekers `,engaging A further object lofthis'invention is to provide new andim'proved manual-power closing device which elimi- -tnates the hazards of excessive burning ofwtheengaging contactsl during a circuit breaker' closing operation.`

A still further object of this'inventionisjto *provide a new and improved-power closing *device `in which 'a Vsource of ffluidpressure of a predetermined value is A`manually created before a circuitbreakerclsing operationcanoccur. v

A still further object of this invention vis to provide a power'closing device in which the fluid lpressure lcanynot `reach values high enough to damage'a circuit breaker :during a'breaker closing operation.

A'still lfurther object of this 'invention is to provide a power closing device employing a valve which prevents the release of iiuid under pressure unless jthere is adequate pressure to insure a successful circuit breaker closing operation. V

vA still further object of this invention is to provide a 'new `and improved circuit lbreaker voperating mecha- `-nisrn which when used with a given group of circuit breakers 'compensates automatically forthneir `different loads so as to provide satisfactory circuit breaker closing -speeds for all.

lA still further object of this invention is togprovide l `a 'single power closing device capable of closing circuit vpower required to close -tle circuit*breakers atiauspeed equal to or-greater"thantheir-norrrial closing speedsfwithout jogging. This closing device, in-"acccrdncewith the invention claimed, `utilizes only a fe`w 'component parts, namely a small manually operatedfhydraulic"pump built-in reservoir and bypass"valve, ana'xurilitor tank which utilizes a gas lled "bladder 'under pressure for energy storage, a closing vvalve `and-liydr`au1icinterlock combination which prevents the initiation "of ya fclosing stroke unless sufhcient energy is available tocomplete the fstroke at the required speed, a relief 'valvewhich ibreakers `having widely diifering force and'speedrequire- :ments- Objects and advantages other than those set forth will `b exapparent from the following vdescription when read in connection with the accompanying drawings, in

which:

Figul yis a view in vertical cross Ysection of a `magnetic blowout type circuit breaker employing the present 1-invention; y y r 1ig4.,2v isa schematic diagram of the manual power circuit breaker closing device shown 4in Fig. "1; and

Y Fig. 3 vis a cro'ss sectional 'View through the reservoir Vof the` pump structureof Fig. 2 taken along the line Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a magnetic blowout type of -circuit breaker employing an arc chute of any suitable form into which the arc is forced by the magnetic blowout field and extinguished. The power cn'- cuit to be interrupted includes relatively movable contacts between which the arc is formed when the contacts separate at the entrance to the arc chute. the contacts comprise a fixed contact structure 11 and coacting movable Contact structure 12. The fixed contact structure is electrically connected to a lead-in conductor stud 13 defining one terminal of the breaker, and the movable contact structure 12 comprises a pivoted switch arm having an arcing contact mounted at one end thereof and electrically connected to a conductor stud 15 defining the other breaker terminal. The pivoted Contact structure 12 is suitably operated between open and closed circuit position by an operating rod 16 that is connected through a crank 17 to a solenoid or other operating means 18.

Fig. 1 illustrates the movable contact structure 12 in contact open position, the coacting main and arcing con- `tacts 20 and 22, respectively, of the movable contact structure 12 being spaced apart from corresponding main and arcing contacts 23 and 25, respectively, of the fixed contact structure 11. A pair of lugs 21 (one of which is shown in Fig. 1) are integrated with arcing contact 22 and extend from opposite sides of a web portion of arcing contact 22. Lugs 21 together with the web portion of the arcing contact 22 form an engaging surface which coacts with that of a loose fitting, self-aligning block of insulating material 24 on the stationary contact structure 11 to limit overtravel of the movable contact structure 12 in the closing direction. In breaker closed position the stationary arcing contact 25 is shunted by stationary main contact 23. Opening of the breaker by the clockwise rotation of the breaker movable contact structure 12 causes in the sequence named separation of the main current carrying contacts 20, 23 and the arcing contacts 22, 25. The power arc is formed at the entrance of an i arc chute 26 of any suitable known type.

Arc chute 26 is illustrated as being provided with magnetic blowout means comprising blowout coils 28 and 29 arranged so as to cause the arc formed between the contacts 22 and 25 to be blown by the magnetic field into arc chute 26. Blowout coil 28 is connected at one end thereof to an arc runner and at the other end thereof immediately adjacent main contact 23. Blowout coil 29 is connected at one end thereof to an arc runner 31 and at the other end thereof to a lower terminal extension 32 through a conductive bar 27.

Upon separation of the arcing contacts 22 and 25 in a circuit interrupting action the arc terminal is transferred from stationary arcing contact 25 to arc runner 30, thereby inserting blowout coil 28 in the arcing circuit traced from the point of connection of blowout coil 28 on the upper terminal block immediately adjacent main contact 23 through blowout coil 28 to arc runner 30, through the arc to movable arcing contact 22. As the arc, now established between arc runner 30 and the movable arcing contact 22, is attenuated by the clockwise rotation of contact structure 12, the arc envelops the lowerrnost portion of arc runner 31 thereby transferring the arc terminal from arcing contact 22 to arc runner 31 and inserting blowout coil 29 in the arcing circuit. The arcing circuit is now completed through the bar 27 which connects the blowout coil 29 with the lower terminal extension 32.

In accordance with the invention claimed, a new and `improved manual power closing device 35 is attached to the circuit breaker structures for closing breakers on an energized system. This portable unit provides sufficient power to close the`circuit breaker contact structures 11, 12 at a proper speed and to insure proper operation of the contacts against the mechanical forces produced by short Specifically, M

circuit currents which might exist at the instant of closgThis portable manual power closing device 35 is a completely self-contained unit requiring no outside source of power for operation and comprises two main parts, namely, the power unit 36 and the uid motor operating means 37. The power unit 36 comprises a stored energy device referred to herein as an accumulator 38, a hand. pump 39, a control valve 40, a pressure gauge 41, asso-V ciated tting 42, valves 43 and 44 and lter 45. The fiuid motor operating means 37, as more clearly shown in Fig..

2, comprises cylinder 46, piston 47 reciprocably mounted in cylinder 46 and biased in one direction by a spring 48, a circuit breaker structure engaging arm 49 for attaching the fluid motor operating means 37 to the breaker structure, and a push rod 50 for transmitting the energy of the fluid motor to the breaker closing solenoid mecha-- nism 18 shown in Fig. 1. A fiexible high pressure hose 101 connects the power unit 36 to the uid motor operating means 37 and thereby provides control of the closing device 35 remote from the circuit breaker. Device 3S may be epuipped with wheels and a handle (not shown) for easy portability, thus providing for convenience in y storage and handling.

More particularly the accumulator 38 comprises a homogeneous, seamless, high pressure shell 54, cylindrical in shape and spun semispherical at either end. One end has an opening for a gas valve 55 which is molded to a pear shaped synthetic rubber bladder 56. The other end of accumulator 38 has an opening 57 provided with a plug assembly. Incorporated in the plug assembly is a poppet valve 59 which seals off opening 57 when the oil is completely expelled from shell 54. This action prevents the bladder 56 from extruding through the opening 57.

The accumulator bladder 56 is precharged with dry nitrogen through the gas valve 55 to approximately twothirds of the desired system operating pressure. With no oil in the accumulator, the bladder fills the entire interior of the accumulator shell 54. As oil is forced into the accumulator 33 from pump 39, it compresses the bladderv 56 and the pressure rises in accordance with Boyles Law. To insure proper operation throughout the temperature range encountered in circuit breaker applications, a commercial oil having a nearly fiat viscosity curve is chosen as the operating medium. Accumulator 38 is connected through a section of pipe 61, fitting 42 and filter 45 containing a replaceable filter element to pump 39.`

Pump 39 is a hand operated device containing a lbuiltin reservoir 62. Its function is to supply oil under pressure to the accumulator.

The control or trigger valve 40 is connected in the pipe system between the accumulator 38 and the fiuid motor operating means 37 for controlling the passage of fiuid from the source to the fluid motor operating means 37. Valve 40 is a noncritical control valve which functions to provide built-in safety features and pressure interlocks. This valve prevents the fiuid from being used to start to close the breaker until sufficient quantity of fiuid under pressure is available in accumulator 38 to complete the closing operation. Valve 40 further holds the stored energy in check until it is released at the election of the operator.

Valve 40 comprises a valve casing or cylinder 65 providing an inlet port 66, an outlet port 67 and an exhaust port 68,y a first valve for controlling the inlet port 66 comprising a valve seat 69 and aball type valve element 70 cooperating with valve seat 69 to form a valve unit, a second valve for controlling the exhaust port 68 comprising a valve seat 71 and a ball type valve element 72 cooperating with valve seat 71 to form a second valve unit, a piston type element 73 reciprocably mounted in casing or cylinder 65, resilient means cornprising springs '774 and 75 for biasing the piston type pressure `pipe 61 'tan -operator Ato increase pressure metia-058 for reducingthe effect of ithe biasing means nfor causing thesource of fluid lto crackthe first Yvalve;andf-.actuate Altheplston type element-73againstthe action of the .springs 74,and75.

Springr 74 of vthe biasing means v-lisqarjranged between =washers 77 seated onrpiston type relement"73wand': a cover fplate-78 of cylinder 65. Spring 75.015 the biasing'rr'iea-nsV vis;rnountedinside of spring 74around a release rod79, :between cover'plate 78 Vand a shouldera80 securedxfto one endnof'rod 79. The otheriend of rrod379:; extends through 'cover' plate :'-78sand1isj provided with .checkglnuts :181. *Spring 75vbiases re1easeIrod.7.9aganst piston 1type element 73. ,I-Iandle76 is iprovided withfanosefrnember :82 which engages checkt-nuts ,81 to 'actuate release, :rod 1.79 against the.biasingfactioneof spring'75 upon counter- .fclockwise rotation of, handle 7 6.

YThe-.piston type velementn'73 is 'providedwithfa piston '20 .-.rod` or plunger .83which extends vaxially through the Yvalve-seat71 and intorengagement with ballrtypevalve .-element 7,2. Valve seats 69 and 71 are axially-aligned along the longitudinal .axis .of cylinder 65. Ball :type :valve-element .72 when Vactuated `to valve open position ,under fthe influence of piston rod 83 and its biasingmeans .engages land actuates ball type valve element 70 4against fvalvefseat69 toyalve closed position. Spring 74 is `designedtov exert sum/cient `force when acting alone, to `prevent ball type'valvefelement 70Lfrom rising from its valve: seat :69 .until pressure inv pipe4 lines 61 isincreased zitozor "isfabove the. .minimum safe loperatinggpressure .'for -`.the circuit :breaker shown or for all circuit'breakers "zwhich are ato vbe :operated by -this .closing'devicef fSlpring :'7511is designedtforuprovidingsuicient forceso `fthatwhen acting with '.spring .'74 it :can prevent balltype valve `element `70 fromxrisin-g goti. its valve aseat. 69 :even

.sat `pressures far above :the maximum #safe operating spressure.

:The Ifrelief .valve I 43 fcomprising -valvecasing f 85 Hproviding an inlet .port'r86 and an outlet `port `87-and a valve seat 188 cooperating with aspring biasedfball ele- 4Irnentf89 opens.to.bypass.oi1 vfrom thezhigh pressure pipe 61 connecting the pump 39..and accumulator'sftoia low y:.pressurepipe'90 connecting the exhaust port 68 of'lvalve `540I andthe reservoir 62 yof vpump '39. When the fmaxi- 'mum safe operating pressure is reached in the ihi'gh vand Vin accumulator 38` relief valve '43 "bypasses yiiuid'under pressurefrom theoutput side of 'pump '39, :to its reservoir'62 fso that itis impossible for Aby continued hand tpumping.

Check `valve 44 comprising a valve casing 95l and. a spring biased valve element `96 is connected at one yend thereof to-an Yexhaust port'97 in casing n65 of valve -140 -andiat the other end thereof to a pipe 98. Pipe982is connected toa base'rnember 99 forming anl integral part of thevalve casing 65fof valve 40 which forms apart ofthe 'high pressure pipe 61 connected to inlet port 66.

Valve A44 plays no direct part during the circuit breaker i closing operation, however, after the breaker is, closed the check valve 44 permits a quick return of the oil inthe lpipe to the reservoir 62 of' pump 39.

'Thebreaker operating cylinder 37 is connected-tothe outlet port'67 of valve 40 througha self-sealing coupler -100 `and pipe 101. The coupler 100 comprisesaspring vloaded poppet valve 102. A springloaded annular sleeve 103'slides on a tubular'valve 104 Ywhich isimmovably "fixed to the coupling housing 105. Poppet valve 102is `firmlyheld against its seat by spring pressure, and sleeve 103 employing a replaceable sealing means 106 is held iirmlyagainst the facel ofthe tubular valve 104`by spring Aand uid pressure. 'An O ring packing '107 lprovides a `seal between the sleeve 103 "andthe housing 105. When fthe-complex' 1100 is coupled .to .the .housing fof the .uid

6 fmotoraoperating'means T37, vjthe -sleeve.-103 and I tubular lvalve 104-,contact the facelof'rtherpoppet valve 'expelling ..-all-air. :lightening the-union nut 1808 forming apart of the housing moves the annular valve sleeve and 5 .,poppet valve `together tofopenfthe fluid-passage.

When an operator==desiresto close the circuit Abreaker withvfthe fmanualclosing device 35 properly affixed to afiche? circuitbreaker@structure; he rotates the handle 112 Y;uloekvviseqtio close;- purnp bypass `valve-113 ,and :then oper- Y10 ates handle" 115 with up and down-motion untilthe 'tindicatorreading ofvrtherpressure gauge 41;b'ecomesf.con Ylstant lThe lmanual closing "device fis then-ready. for a breaker closing operation. @Rotation l`of ihiandle 76 counterclockwise triggers valve 40 by lifting rod 79 and shoulder 80 oi of pistonf'ftype element 73 to compress spring 75. When the reaction of spring 75 is removed rirorn., pist-on .typelelement 73 the only remainingfforce on element 73.and.ball,type-e1ements'70 and yI .Ifris.-the'bias'ing effect of spring 74. fflheigoil .pressurewithinfthepipe-l and accumulator 38 being within the safe operati-ng range overcomesthe reaction of spring 74 and lifts ball type `lementi70 'fromitswalve seat 6 9. When ball type ele- "ment' '70.: 'moves 'upward by the `iiuid pressure acting yon "itspre'ssu're responsivev surface, it exposes the larger 'sur- "face ofball 'type element 72 whichis forced upward'by the pressure to engage its valve seat 71 and form a 'pressuretight seal lso that uid under pressure in valve 40k cannotbelost through the exhaust port 68. Once vthe valvegforrned 'byvalveseat 69'and ball type element 70 'hasbe'en cracked, the circuit breaker closing'operation "will go Lto V'completion regardless of how briey the A"releaselev'er'orhandle 76Y'holds`the `force` 'of spring75 off of piston type element 73.

Partial operations orii'oggin'g are not possible. This "'35 is due to the dierence in areas upon which theitluid .45 finlet port L66 falso "acts onp'iston type-element 73.to

.'force element73".upward`against the reaction of springs H74fan'd 75"-toaid"nquickly opening inlet port' 66 and closing exhaust port 68 with ball type element AA72. The 'across sectional area of port "68 is `relatively -smalL Therefore, thevolume fofuidunder pressure ypassing l'through-pip'e 90 isof'allrnited "quantity during piston operation. ln other words, during any valve operation, theuidpassinglintothe cylinder below piston 73fislof Asulicientypre'ssureand volume that it can readily/.operate piston 73 even `though'a part of it may be'bledthrough lines `68--90 to the-reservoir. Fluid under pressure in lcylinder '65 passes through outlet port 67, pipe 101, lcoupler'l100 `toope'ratingcylinder 37`t0 actuate piston VY?! -ofcylin'der 37` yagainst the'biasing effect of spring 48 A*thereby actuating a push rod 110 and a lever arm .111 and solenoid vltvto close the lcircuit breaker contactsv 11 and 12.

Toreturn 'piston 4710i` theiluid motor operating means 37 vto the position shown, i after the circuit brealterfhas closed the operatorrotates`a`fvalvehandle 112=counterv clockwise which opens -a pump -check valve 113 to provide a means for 'emptying back into the pump reservoir 62 theremainingfluid storedin the 'accumulator 3S. 'When pressure in the header or base member`99 falls 'below lfthat intheuid motor operating means 37 checkvalve 444lopens to reduce theuidpressure 'in pipe lllcausing vspring-481m force piston 47 from left tofright in cylinder k146,"therel3y forcing Vtheluid in cylinder'46'bafck through l.coupler .100 into` pipe 101. The .consequent displacement of uid in the pipe 101 is communicated. lay-valve 7 housing 65, check valve 44, base member 99, fitting 42 'and filter 45 to pump reservoir 62. Device 35 is then fully reset and ready for another accumulator charging operation.

The quick coupler 100 is so designed that the hose or pipe 101 may be quickly disconnected from fiuid motor means 37 without loss of fiuid from pipe 101 and may be quickly reconnected to other fiuid motor operating means designed for operating other types of circuit breaker structures.

An orifice 114 at the entrance of the fiuid motor operating means 37 is of such a diameter with respect to the diameter of piston 47 that Pfi'po :P where pf=fiuid pressure on piston 47 required to close the circuit breaker at maximum safe closing speed.

po=pressure drop through orifice 114.

P=source pressure.

Such a fluid motor operating means, having an orifice proportioned in accordance with the foregoing equation for a particular circuit breaker, is not limited in its application to that circuit breaker alone, for the following reasons.

For the fiuid motor operating means of this invention, in which the entire hydraulic system lies in a substantially horizontal plane and therefore has a gh (g is gravitational acceleration and h is velocity head) component equal to zero and in which the viscosity p of the fluid is constant, Bemoullis fundamental equation may be written po=pressure drop through orifice 114.

K=a constant.

V- fclosing velocity of piston 47=closing speed of the circuit breaker mechanism.

Thus, when the fluid motor operating means is required to close a circuit breaker having a greater closing force demand than that of the circuit breaker for which the orifice was originally designed, the consequent reductiOn in the velocity of its piston causes an exponential reduction of the pressure drop through its orifice, thereby releasing the additional force necessary to close the circuit breaker.

In the event that a system fault occurs during the circuit breaker closing operation and the magnitude of the ensuing fault current is such as to electromagnetically retard full engagement of the circuit breaker contacts, consequent reduction in the closing velocity of piston 47 will, likewise, release the additional force necessary to fully close the conta-cts of the circuit breaker.

Therefore, such a fiuid motor operating means can be safely applied to circuit breakers having closing speeds and closing force demands which differ widely from those of the circuit breaker for which its orifice was originally designed, provided that in each case the total kinetic energy demand is substantially the .same as that of the original breaker.

For circuit breakers having kinetic energy demands substantially greater than that of the original breaker, orifices of correspondingly greater diameter are required, the limiting condition being that imposed by a circuit breaker whose kinetic energy demand is substantially equal to the total potential energy Stored in the accumulator.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In an operating mechanism for circuit breakers, a motor operable by fiuid under pressure and comprising a cylinder and a piston movably arranged therein, a source of fluid under pressure, means for admitting uid under pressure from said source to said cylinder to actuate said breaker in Contact closing direction, said means comprising a valve casing providing an inlet port, an outlet port and an exhaust port, a first valve for controlling said inlet port, said first valve comprising a first valve seat and a first ball type valve element cooperating with said first valve seat, a second valve for controlling said exhaust port, said second valve comprising a second valve seat and a second ball type valve element cooperating with said second valve seat, a piston type element reciproeably mounted in said casing, resilient means for biasing said piston type element in one direction to actuate said second valve element to valve open position, said second valve element upon movement to valve open position engaging and actuating said first valve element to valve closed position, means defining a passage from said source to said cylinder, said casing forming an integral part of said passage, a pressure responsive surface provided on said first valve element upon which the pressure in said passage acts to actuate said first valve element to valve open position against the action of said biasing means to connect said inlet port to said outlet port, a pressure responsive surface provided on said piston type element upon which the pressure in said casing acts to actuate said piston type element against the action of said biasing means, said second valve element being actuated to valve closed position to close said exhaust port only upon cracking of said first valve element and movement of said piston type element against the action of said biasing means, means for controlling the pressure acting on said surface of said first valve element so that the pressure does not exceed a predetermined value, and means for reducing the effect of said biasing means for causing'said source of fluid to crack said first valve and actuate said piston type element against the action of said biasing means.

2. In an operating mechanism for circuit breakers, a motor operable by fluid under pressure and comprising a cylinder and a piston movably arranged therein, a source of fluid under pressure, means for admitting uid under pressure from said source to said cylinder to actuate said breaker in `contact closing direction, said means comprising a valve casing providing an inletl port, an outlet port and an exhaust port, a first valve for controlling said inlet port, said first valve comprising a first valve seat and a first ball type valve element cooperating with said first valve seat, a second valve for controlling said exhaust port, said second valve comprising a second valve seat and a second ball type valve element cooperating with said second valve seat, a piston type element reciprocably mounted in said casing, resilient means comprising a first spring and a second spring for biasing said piston type element in one direction to lock said first valve element in valve closed position and said second valve element in valve open position, means defining a passage from said source to said cylinder, said casing forming an integral part of said passage, a pressure responsive surface provided on said first valve element upon which the pressure in said passage acts to actuate said first valve element to valve open position against the 'action `0f said biasing means to connect Said inlet port to said outlet port, said second valve element being actuated to valve closed position to close said exhaust port only upon cracking of said first valve element, and means for controlling the pressure acting on said surface of said first valve element so that the pressure does not exceed a predetermined value, and means for removing the biasing effect of said second spring from said piston type element for causing said source of uid to crack said first valve, actuate said piston type element against v 9 the biasing action of said first spring and close said second valve.

3. In an operating mechanism for circuit breakers, a motor operable by fluid under pressure and comprising a. cylinder and a piston movably arranged therein, a source of fiuid under pressure, means for admitting fluid under pressure from said source to said cylinder to actuate said breaker in contact closing direction, said means comprising a valve casing providing an inlet port, an outlet port and an exhaust port, a first valve for controlling said inlet port, said first valve comprising a first valve seat and a first ball type valve element cooperating with said first valve seat, a second valve for controlling said exhaust port, said second valve comprising a second valve seat and a second ball type valve element cooperating with said second valve seat, a piston type element reciprocably mounted in said casing, resilient means comprising a first spring and a Second spring for biasing said piston type element in one direction to actuate said second valve element to valve open position, said second valve element upon movement to valve open position engaging and actuating said first valve element to valve closed position, means defining a passage from said source to said cylinder, said casing forming an integral part of 4said passage, a pressure responsive surface provided on said first valve element upon which the pressure in said passage acts to actuate said first valve element to valve open position against the action of said biasing means to connect said inlet port to said outlet port, a pressure responsive surface provided on said piston type element upon which the pressure in said casing acts to actuate said piston type element against the action of said biasing means, said second valve element being actuated to valve closed position to close said exhaust port only upon cracking of said first valve element and movement of said piston type element against the action of said biasing means, and means for controlling the pressure acting on said surface of said first valve element so that the pressure does not exceed a predetermined value, and means for removing the biasing effect of said second spring from said piston type element for causing said source of fluid to crack said first valve and actuate said piston type element against the biasing action of said first spring and close said second valve.

4. In an operating mechanism for circuit breakers, a motor operable by uid under pressure and comprising a cylinder and piston movably arranged therein, said cylinder providing an orifice for controlling the rate of flow of fiuid into said cylinder, said orifice being of a predetermined size so that upon varying closing speeds and force demands 0f the different circuit breakers said orifice causes a change in the pressure drop through said orifice thereby releasing substantially the force needed to close each of the circuit breakers at its predetermined speed, a source of fluid under pressure, means for admitting fiuid under pressure from said source through said orifice to said cylinder to actuate said breaker in conta-ct closing direction, said means comprising a valve casing providing an inlet port, an outlet port and an exhaust port, a second valve element for controlling said exhaust port, a piston type element movably arranged in said casing, resilient means for biasing said piston type element in one direction to lock said first valve element in valve closed position and said second valve element in valve open position, means defining a passage from said source to said cylinder, said casing forming an integral part of said passage, a pressure responsive surface provided on said first valve element upon which the pressure in said passage acts to actuate said first valve element to valve open position against the action of said biasing means to connect said inlet port to said outlet port, said second valve element being actuated to valve closed position to close said exhaust port only upon cracking of said first valve element, and means for controlling the pressure acting on said surface of said first valve element so that the pressure does not exceed a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS 768,939 Hall Aug. 30, 1904 1,138,278 Castle May 4, 1915 1,808,431 Osborne June 2, 1931 1,955,154 Temple Apr. 17, 1934 2,347,379 Teeter Apr. 25, 1944 2,437,991 Baston Mar. 16, 1948 2,446,691 Clyde et al. Aug. 10, 1948 2,526,406 Pfauser Oct. 17, 1950 2,619,523 Bonine et al Nov. 25, 1952 2,660,984 Zumwalt Dec. 1, 1953 2,662,134 Umphrey Dec. 8, 1953 

